1. Field of the Invention
The present invention relates to an integrator circuit, and more particularly, to an integrator circuit that has a high resolution and a small phase difference.
2. Description of Related Art
An integrator is a commonly used analog circuit for performing a mathematical operation of integration. Typically, a voltage integrator is formed by an electric circuit composed of capacitors and resistors. Since a current passing through a capacitor is relative to a rate of voltage change, i.e., a result of differentiating voltage at a time, a voltage across the capacitor is considered as a result of the operation of integration for an input voltage and a voltage across the resistor is considered as a differential result for the input voltage. In the related art, an operational amplifier is often applied in an integrator circuit or a differentiator circuit for adjusting the input impedance and the output impedance of the integrator circuit.
Another well-known low frequency integrator is equipped with an Analog to Digital Converter (ADC) to convert an analog signal to a digital signal before the operation of integration is performed. However, the accuracy of results obtained from the integrator circuit is restricted by the resolution of the ADC. Even though the accuracy of the integrator can be enhanced by utilizing the ADC of a higher resolution, the associated cost for the integrator circuit increases accordingly. In addition, the conventional integrators generally require a low-pass filter to filter out high-frequency portions of signals before the performance of the operation of the integration. However, for the lower-frequency portions of the signal to be filtered out the integrators require larger capacitance, increasing overall manufacturing costs of such integrators and causing larger difference in phase and low frequency oscillation destabilizing system control.